Adding to the end of the gnu ld library search paths

Question

I know how to add to GNU ld's library search path using the -Ldir option and use it extensively. But as far as I can tell from reading the manuals of gcc and ld, there is no way to add to the end of the list of library search paths.

The -L option adds to the beginning, after which it searches the default system library paths. But I want to add a look-here-if-you-can't-find-it-anywhwere-else path. Is there any way to do that with ld?

I can imagine a hacky-crap solution that extracts all standard library dirs (using -print-search-dirs) and adds them to the list of -L search dirs in the order I desire, ahead of their implied duplicates as default search paths...

But there must be a better way...

score 0 · Answer 1 · answered Sep 12 '12 at 13:33

0

The /etc/ld.so.conf file has a system-wide list of directory paths where libraries are searched at compile-time, the newline separated order of entries of such file is honored.

After modifying that file you must run ldconfig (as root) so that the new setting becomes active.

answered Sep 12 '12 at 13:33

Jaromil

76
5

This sounds **very** linux-specific. It may work for particular contexts, though. – Bryce Schober Sep 18 '12 at 00:23

score 0 · Answer 2 · answered Feb 19 '12 at 20:43

I don't think you can do exactly what you want. However, what if you force all of the symbols in the libraries you're including to be weak with the following ld flag:

 -weak_library path_to_library
             This is the same as listing a file name path to a library on
             the link line except that it forces the library and all ref-
             erences to it to be marked as weak imports.

This way, if other libraries are included with stronger symbols, they'll override the symbols in look-here-if-you-can't-find-it-anywhwere-else.so. If there are no stronger symbols defined in the libraries mentioned in LD_LIBRARY_PATH, the weak symbols in look-here-if-you-can't-find-it-anywhwere-else.so will be used.

Now if only I could remember the particular context that triggered this question... — Bryce Schober, Sep 18 '12 at 00:21

Adding to the *end* of the gnu ld library search paths

2 Answers2

Adding to the end of the gnu ld library search paths